Data carriers, such as identification cards and credit cards are commonly and increasingly used for various purposes. An identification card should offer great security against counterfeiting because it is used to verify aspects of a person's personal identity. Also other types of data carriers should, naturally, offer great security against counterfeiting. Despite the requirement that the data carriers should be impossible or at least very difficult to forge, they should be easy to check visually and should also be easy to mass produce. These characteristics are difficult to meet at the same time.